Oligosaccharide-Peptide ligation of Glycosyl thiolates with dehydropeptides:synthesis of S-Linked Mucin-Related Glycopeptide Conjugates

摘要

A chemoselective strategy for oligosaccharide-peptide ligation is described in which alpha-thio analogues of mucin-related glycoconjugates can be readily accessed through site-selective conjugate addition of complex oligosaccharide thiolates to dehydroalanine-containing peptides.The efficiency of teh ligation is highlighted by the rapid convergent assembly of thio-isosteres of the four tumor-associated carbohydrate antigene,T_N,T,ST_N,and 2,6-ST,as a pair of diastereoisomers at the newly formed cysteine stereocenter.The process proceeds in high yield and with complete retention of the alpha-anomeric configuration.